Electro-luminescent arrangements with thiophene carboxylate metal complexes

ABSTRACT

Electroluminescent assembly comprising a substrate, an anode, an electroluminescent element and a cathode, where at least one of the two electrodes is transparent in the visible spectral region and the electroluminescent element comprises one or more zones selected from the group consisting of a hole injection zone, a hole transport zone, an electroluminescent zone, an electron transport zone and an electron injection zone in the specified order, where each of the zones present may also assume functions of the other zones mentioned, characterized in that the electroluminescent element contains a thiophenecarboxylate-metal complex.

This application has been filed under 35 U.S.C. §371 based upon PCT/EP99/06151 filed Aug. 23, 1999.

An electroluminescent (EL) assembly is characterized in that it emits light and current flows when an electric potential is applied. Such assemblies have long been known in industry under the name “light-emitting diodes” (LEDs). The emission of light results from positive charges (holes) and negative charges (electrons) recombining with emission of light.

In the development of light-emitting components for electronics or optics, use is at present mainly made of inorganic semiconductors such as gallium arsenide. Dot-shaped display elements can be produced on the basis of such substances. Large-area assemblies are not possible.

Apart from the semiconductor light-emitting diodes, electroluminescent assemblies based on vapour-deposited low molecular weight organic compounds are known (U.S. Pat. Nos. 4,539,507, 4,769,262, 5,077,142, EP-A 0 406 762, EP-A 0 278 758, EP-A 0 278 757).

Furthermore, polymers such as poly-(p-phenylenes) and poly-(p-phenylene-vinylenes) (PPV)) have been described as electroluminescent polymers: G. Leising et al., Adv. Mater. 4 (1992) No. 1; Friend et al., J. Chem. Soc., Chem. Commun. 32 (1992); Saito et al., Polymer, 1990, Vol. 31, 1137; Friend et al., Physical Review B, Vol. 42, No. 18, 11670 or WO-A 90/13148. Further examples of PPVs in electroluminescence displays are described in EP-A 0 443 861, WO-A 92/03490 and 92/03491.

EP-A 0 294 061 discloses an optical modulator based on polyacetylene.

To produce flexible polymer LEDs, Heeger et al have proposed soluble conjugated PPV derivatives (WO-A 92/16023).

Polymer blends of different compositions are likewise known: M. Stolka et al., Pure & Appt. Chem., Vol. 67, No. 1, pp 175-182, 1995; H. Bässler et al., Adv. Mater. 1995, 7, No. 6, 551; K. Nagai et al., Appl. Phys. Lett. 67 (16), 1995, 2281; EP-A 0 532 798.

The organic EL assemblies generally contain one or more layers of organic charge transport compounds. The in-principle structure in the order of the layers is as follows:

1 support, substrate

2 base electrode

3 hole injection layer

4 hole transport layer

5 light-emitting layer

6 electron transport layer

7 electron injection layer

8 top electrode

9 contacts

10 sheathing, encapsulation.

The layers 3 to 7 represent the electroluminescent element.

This structure represents the most general case and can be simplified by leaving out individual layers so that one layer takes on a plurality of functions. In the simplest case, an EL assembly consists of two electrodes between which there is located an organic layer which fulfils all functions including the emission of light. Such systems are described, for example, in the application WO-A 90/13148 on the basis of poly-(p-phenylene-vinylene).

Multilayer systems can be built up by vapour deposition methods in which the layers are applied successively from the gas phase or by means of casting processes. Owing to the higher process speeds, casting processes are preferred. However, partial dissolution of a layer which has already been applied when the next layer is applied on top can present a difficulty in certain cases.

It is an object of the present invention to provide electroluminescent assemblies having a high light flux in which novel metal complexes having improved solubility in customary solvents are used as emitters and/or electron conductors. These novel metal complexes should also be able to be applied by vapour deposition from the gas phase.

It has been found that electroluminescent assemblies containing the metal complexes specified below meet these requirements. In the following, the term zone is equivalent to the term layer.

The present invention accordingly provides an electroluminescent assembly comprising a substrate, an anode, an electroluminescent element and a cathode, where at least one of the two electrodes is transparent in the visible spectral region and the electroluminescent element comprises one or more zones selected from the group consisting of a hole injection zone, a hole transport zone, an electroluminescent zone, an electron transport zone and an electron injection zone in the specified order, where each of the zones present may also assume functions of the other zones mentioned, characterized in that the electroluminescent element contains a thiophenecarboxylate-metal complex.

The hole injection zone preferably contains an uncharged or cationic polythiophene of the formula (I)

where

Q¹ and Q² represent, independently of one another, hydrogen, substituted or unsubstituted (C₁-C₂₀)-alkyl, CH₂OH or (C₆-C₁₄)-aryl or

Q¹ and Q² together represent —(CH₂)_(m)—CH₂— where m 0 to 12, preferably from 1 to 5, or (C₆-C₁₄)-arylene, and

n represents an integer from 2 to 10,000, preferably from 5 to 5000.

The hole conductor zone adjoining the hole injection zone preferably contains one or more aromatic tertiary amino compounds, preferably substituted or unsubstituted triphenylamine compounds, particularly preferably 1,3,5-tris(aminophenyl)benzene compounds of the formula (II).

The zones or zone located between the hole injection zone and the cathode can also assume a plurality of functions, i.e. one zone can comprise, for example, hole-injecting, hole-transporting, electroluminescent, electron-transporting and/or electron-injecting substances.

The electroluminescent element can additionally contain one or more transparent polymeric binders.

The substituted or unsubstituted 1,3,5-tris(aminophenyl)benzene compound preferably represents an aromatic tertiary amino compound of the general formula (II)

in which

R² represents hydrogen, substituted or unsubstituted alkyl or halogen,

R³ and R⁴ represent, independently of one another, substituted or unsubstituted (C₁-C₁₀)-alkyl, alkoxycarbonyl-substituted (C₁-C₁₀)-alkyl or substituted or unsubstituted aryl, aralkyl or cycloalkyl.

R³ and R⁴ preferably represent, independently of one another, (C₁-C₆)-alkyl, in particular methyl, ethyl, n- or iso-propyl, n-, iso-, sec- or tert-butyl, (C₁-C₄)-alkoxycarbonyl-(C₁-C₆)-alkyl such as methoxycarbonyl-, ethoxycarbonyl-, propoxycarbonyl- or butoxycarbonyl-(C₁-C₄)-alkyl, or unsubstituted or (C₁-C₄)-alkyl- and/or (C₁-C₄)-alkoxy-substituted phenyl-(C₁-C₄)-alkyl, naphthyl-(C₁-C₄)alkyl, cyclopentyl, cyclohexyl, phenyl or naphthyl.

Particularly preferably, R³ and R⁴ represent, independently of one another, unsubstituted phenyl or naphthyl or phenyl or naphthyl substituted in each case by from 1 to 3 methyl, ethyl, n-, iso-propyl methoxy, ethoxy, n- and/or iso-propoxy groups.

R² preferably represents hydrogen, (C₁-C₆)-alkyl, for example methyl, ethyl, n- or iso-propyl, n-, iso-, sec- or tert-butyl, or chlorine.

Such compounds and their preparation are described in U.S. Pat No. 4,923,774 for use in electrophotography, which patent is hereby expressly incorporated by reference into the present description. The tris-nitrophenyl compound can be converted into the tris-aminophenyl compound by, for example, generally known catalytic hydrogenation, for example in the presence of Raney nickel (Houben-Weyl 4/1C, 14-102, Ullmann (4) 13, 135-148). The amino compound is reacted with substituted halogenobenzenes in a generally known manner.

As examples, mention may be made of the following compounds:

Apart from the tertiary amino compound, it is possible, if desired, to use further hole conductors, for example in the form of a mixture with the tertiary amino compound, for building up the electroluminescent element. It is possible here to use either one or more compounds of the formula (II), with mixtures of isomers also being included, or else mixtures of hole transport compounds with compounds of tertiary amino compounds having the general formula (II) and different structures.

A listing of possible hole injection materials and hole conductor materials is given in EP-A 0 532 798.

In the case of mixtures of the aromatic amines, the compounds can be used in any ratio.

Examples which may be mentioned are:

Materials which have hole-conducting properties and can be used in pure form or as components of mixtures with the tertiary amino compounds are, for example, the following compounds, where X¹ to X⁶ represent, independently of one another, H, halogen, alkyl, aryl, alkoxy, aryloxy.

These and further examples are described in J. Phys. Chem. 1993, 97, 6240-6248 and Appl. Phys. Lett., Vol. 66, No. 20, 2679-2681.

In general, various amines having different basic structures and/or different substitution patterns can be mixed.

X¹ to X⁶ preferably represent, independently of one another, hydrogen, fluorine, chlorine, bromine, (C₁-C₁₀)-, in particular (C₁-C₄)-alkyl or -alkoxy, phenyl, naphthyl, phenoxy and/or naphthyloxy. The aromatic rings may be monosubstituted, disubstituted, trisubstituted or tetrasubstituted by identical or different radicals and by at least one radical X¹ to X⁶.

The polythiophenes of the structural repeating unit of the formula (I) are known (cf. EP-A 0 440 958 and 0 339 340). The preparation of the dispersions or solutions used according to the invention is described in EP-A 0 440 957 and DE-A 42 11 459.

The polythiophenes in the dispersion or solution are preferably used in cationic form as is obtained, for example, by treatment of the uncharged thiophenes with oxidants. Customary oxidants such as potassium peroxodisulphate are used for the oxidation. As a result of the oxidation, the polythiophenes acquire positive charges which are not shown in the formulae since their number and their position cannot be determined unambiguously. They can be prepared directly on supports as described in EP-A 0 339 340.

Q¹ and Q² in formula (I) preferably represent —(CH₂)_(m)—CH₂— where m=1 to 4, very particularly preferably ethylene.

Preferred cationic or uncharged polydioxythiophenes comprise structural units of the formula (Ia) or (Ib)

where

Q³ and Q⁴ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₈)-alkyl, preferably (C₁-C₁₀)-, in particular (C₁-C₆)-alkyl, (C₂-C₁₂)-alkenyl, preferably (C₂-C₈)-alkenyl, (C₃-C₇)-cycloalkyl, preferably cyclopentyl, cyclohexyl, (C₇-C₁₅)-aralkyl, preferably phenyl-(C₁-C₄)-alkyl, (C₆-C₁₀)-aryl, preferably phenyl, naphthyl, (C₁-C₁₈)-alkoxy, preferably (C₁-C₁₀)-alkoxy, for example methoxy, ethoxy, n-or iso-propoxy, or (C₂-C₁₈)-alkyloxy ester and

Q⁵ and Q⁶ represent, independently of one another, hydrogen or (C₁-C₁₈)-alkyl, preferably (C₁-C₁₀)-, in particular (C₁-C₆)-alkyl, (C₂-C₁₂)-alkenyl, preferably (C₂-C₈)-alkenyl, (C₃-C₇)-cycloalkyl, preferably cyclopentyl, cyclohexyl, (C₇-C₁₅)-aralkyl, preferably phenyl-(C₁-C₄)-alkyl, (C₆-C₁₀)-aryl, preferably phenyl, naphthyl, (C₁-C₁₈)-alkoxy, preferably (C₁-C₁₀)-alkoxy, for example methoxy, ethoxy, n- or iso-propoxy, or (C₂-C₁₈)-alkyloxy ester which are each substituted by at least one sulphonate group, where, if Q⁵ represents hydrogen, Q⁶ is not hydrogen and vice versa,

n represents an integer from 2 to 10,000, preferably from 5 to 5000.

Particular preference is given to cationic or uncharged polythiophenes of the formulae (Ia-1) and (Ib-1)

where

Q⁵ and n are as defined above.

To balance the positive charge, the cationic form of the polythiophenes contains anions, preferably polyanions.

Polyanions present are preferably the anions of polymeric carboxylic acids such as polyacrylic acids, polymethacrylic acid or polymaleic acids and polymeric sulphonic acids such as polystyrenesulphonic acids and polyvinylsulphonic acids. These polycarboxylic and polysulphonic acids can also be copolymers of vinylcarboxylic and vinylsulphonic acids with other polymerizable monomers such as acrylic esters and styrene.

The counterion is particularly preferably the anion of polystyrenesulphonic acid.

The molecular weight of the polyacids on which the polyanions are based is preferably from 1000 to 2,000,000, particularly preferably from 2000 to 500,000. The polyacids or their alkali metal salts are commercially available, for example polystyrenesulphonic acids and polyacrylic acids, or else can be prepared by known methods (see, for example, Houben-Weyl, Methoden der organischen Chemie, Volume E 20 Makromolekulare Stoffe, part 2 (1987), p. 1141 f).

In place of the free polyacids required for forming the dispersions of polydioxythiophenes and polyanions, it is also possible to use mixtures of alkali metal salts of the polyacids and corresponding amounts of monoacids.

In the case of the formulae (Ib) and (Ib-1), the polydioxythiophenes bear positive and negative charges in the monomer unit itself.

The assemblies of the invention may, if desired, contain polymers and/or copolymers as binders, for example polycarbonates, polyester carbonates, copolymers of styrene such as SAN or styrene acrylates, polysulphones, polymers based on vinyl-containing monomers, for example poly(meth)acrylates, polyvinylpyrrolidone, polyvinylcarbazole, vinyl acetate and vinyl alcohol polymers and copolymers, polyolefins, cyclic olefin copolymers, phenoxy resins, etc. It is also possible to use mixtures of various polymers. The polymeric binders have molecular weights of from 10,000 to 2,000,000 g/mol, are soluble and film-forming and are transparent in the visible spectral region. They are described, for example, in Encyclopedia of Polymer Science and Engineering, 2nd Ed., a Wiley-Interscience publication. They are usually used in an amount of up to 95% by weight, preferably up to 80% by weight, based on the total weight of the electroluminescent elements.

The thiophenecarboxylate-metal complex is preferably a compound of the general formulae (III)a to (III)g

where

Me represents a metal,

V₁, V₂, V₃ and V₄ each represent a substituted or unsubstituted and/or branched or unbranched alkylene radical or a substituted or unsubstituted thiophene or oligothiophene radical,

V₅ represents an alkylene radical or a single bond,

Z represents, independently in the two forms, atoms which complete a moiety which comprises at least 2 fused rings,

R₁ to R₂₀ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₆)-alkyl or (C₁-C₁₀)-alkoxy, where, in the case of alkoxy-substitution, adjacent substituents may be linked to form a ring, and

n represents an integer.

It is generally possible to utilize trivalent metals which are known to form chelates.

The metal can be aluminium, gallium, indium or a lanthanoid.

Z completes a heterocyclic moiety which comprises at least two fused rings of which one is an azole or azine ring; further additional aliphatic or aromatic rings may be bound to the two fused rings.

The component particularly preferably represents a compound of the general formulae (III)h to (III)n

in which

R₂₁ particularly preferably represents (C₁-C₁₆)-alkyl, and

R₂₂ to R₂₆ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₆)-alkyl or acyl or halogen or substituted or unsubstituted aryl or cyano or sulphonamido or a substituted or unsubstituted amino group,

R₂₇ to R₄₀ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₆)-alkyl or (C₁-C₁₀)-alkoxy, where, in the case of alkoxy-substitution, adjacent substituents may be linked to form a ring, and

Me particularly preferably represents Al, Ga or In.

The thiophenecarboxylate-metal complex very particularly preferably represents a compound of the general formulae (III) h to (III) n

in which

R₂₁ very particularly preferably represents (C₁-C₁₀)-alkyl and

R₂₂ to R₂₆ very particularly represent, independently of one another, hydrogen, substituted or unsubstituted (C₁-C₁₀)-alkyl or acyl or sulphonamido,

R₂₇ to R₄₀ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₀)-alkyl or (C₁-C₁₀)-alkoxy, where, in the case of alkoxy-substitution, adjacent substituents may be linked to form a ring, and

Me very particularly preferably represents Ga,

V₃ and V₄ each very particularly represent an alkylene radical,

V₅ very particularly represents a direct linkage,

k very particularly preferably represents an integer from 1 to 10.

Examples which may be mentioned are:

It is possible to use one or more compounds of the formulae B1 to B13.

Some of the 8-hydroxyquinoline ligands are commercially available or they can be prepared by known methods of organic chemistry (R. G. W. Hallingshead, Vol.1, Chap.6, Butterworths, London (1954)). The metal complexes can likewise be prepared by known methods (L. S. Sapachak et al., J. Phys. Chem. 100, 177766 (1996) and H. Schmidbauer et al., Z. Naturforsch. 46b, 1065 (1991)).

Some of the thiophene derivatives are commercially available or they can be prepared by known methods of organic chemistry.

To produce the electroluminescent element, the thiophenecarboxylate-metal complex and, if desired, the tertiary amino compound and the binder are dissolved in a suitable solvent and applied to a suitable substrate by casting, doctor blade coating or spin coating. However, the metal complex can also be applied, if desired, as a separate layer by a vapour deposition process. The substrate can be, for example, glass or a plastic material which is provided with a transparent electrode. As plastic material, it is possible to use, for example, a film of polycarbonate, polyester such as polyethylene terephthalate or polyethylene naphthalate, polysulphone or polyimide.

Suitable transparent electrodes are

a) metal oxides, for example indium-tin oxide (ITO), tin oxide (NESA), zinc oxide, doped tin oxide, doped zinc oxide, etc.,

b) semitransparent metal films, for example Au, Pt, Ag, Cu etc.,

c) conductive polymer films such as polyanilines, polythiophenes, etc.

The metal oxide electrodes and the semitransparent metal film electrodes are applied in a thin layer by techniques such as vapour deposition, sputtering, platination, etc. The conductive polymer films are applied from the solution by techniques such as spin coating, casting, doctor blade coating, etc.

The thickness of the transparent electrode is from 3 nm to a number of μm, preferably from 10 nm to 500 nm.

The electroluminescent layer is applied as a thin film directly to the transparent electrode or to any charge transport layer which is present. The thickness of the film is from 10 to 500 nm, preferably from 20 to 400 nm, particularly preferably from 50 to 250 nm.

A further charge transport layer can be inserted on the electroluminescent layer before a counterelectrode is applied.

A listing of suitable charge-transporting intermediate layers, which may be hole conductor and/or electron conductor materials and may be present in polymeric or low molecular weight form, if desired as a blend, is given in EP-A 0 532 798. Particularly suitable materials are specifically substituted polythiophenes which have hole transport properties. They are described, for example, in EP-A 0 686 662.

The content of low molecular weight hole conductor in a polymeric binder can be varied in the range from 2 to 97% by weight; the content is preferably from 5 to 95% by weight, particularly preferably from 10 to 90% by weight, in particular from 10 to 85% by weight. The hole injection or hole conduction zones can be deposited using various methods.

Film-forming hole conductors can also be used in pure form (100% pure). If desired, the hole injection or hole conduction zone may also contain proportions of an electroluminescent substance.

Blends which consist exclusively of low molecular weight compounds can be vapour-deposited; soluble and film-forming blends, which may contain a binder in addition to low molecular weight compounds, can be deposited from solution, for example by means of spin coating, casting or doctor blade coating.

It is also possible to apply emitting and/or electron-conducting substances in a separate layer on the hole conduction layer. Here, an emitting substance can also be added as dopant to the layer containing the compound (II) and an electron-conducting substance can be applied in addition. An electroluminescent substance can also be added to the electron injection or electron conduction layer.

The content of low molecular weight electron conductors in the polymeric binder can be varied in the range from 2 to 95% by weight; the content is preferably from 5 to 90% by weight, particularly preferably from 10 to 85% by weight. Film-forming electron conductors can also be used in pure form (100% pure).

The counterelectrode comprises a conductive substance which may be transparent. Preference is given to metals, for example Al, Au, Ag, Mg, In, etc., or alloys and oxides of these which can be applied by techniques such as vapour deposition, sputtering and platination.

The assembly of the invention is brought into contact with the two electrodes by means of two electric leads (for example metal wires).

On application of a DC potential in the range from 0.1 to 100 volts, the assemblies emit light having a wavelength of from 200 to 2000 nm. They display photoluminescence in the range from 200 to 2000 nm.

The assemblies of the invention are suitable for producing units for lighting and for display of information.

EXAMPLE 1

A solution of 1.27 g (8 mmol) of recrystallized 8-hydroxyquinaldine and 5.68 g (40 mmol) of 2-thiopheneacetic acid in 150 ml of distilled water is added dropwise to a solution of 1.67 g (4 mmol) of gallium(III) nitrate hydrate in 50 ml of distilled water. The precipitate which forms is separated off and washed with water. Drying gives a yellow crystalline solid which has a blue fluorescence.

Yield: 0.86 g (1.63 mmol{circumflex over (=)}40.8% of theory).

EXAMPLE 2

A solution of 1.27 g (8 mmol) of recrystallized 8-hydroxyquinaldine and 6.0 g (40 mmol) of sodium 2-thiophenecarboxylate in 100 ml of distilled water is added dropwise to a solution of 1.67 g (4 mmol) of gallium(III) nitrate hydrate in 50 ml of distilled water. The precipitate which forms is separated off and washed with water. Drying gives a yellow crystalline solid which has a blue fluorescence.

Yield: 0.97 g (1.9 mmol{circumflex over (=)}47.2% of theory).

EXAMPLE 3

A solution of 1.27 g (8 mmol) of recrystallized 8-hydroxyquinaldine and 5.0 g (26.8 mmol) of 3-thienylmalonic acid in 150 ml of distilled water is added dropwise to a solution of 1.67 g (4 mmol) of gallium(III) nitrate hydrate in 150 ml of distilled water. The precipitate is separated off and washed with water. Drying gives a yellow crystalline solid which has a yellowish green fluorescence.

Yield: 0.51 g (0.53 mmol{circumflex over (=)}26.5% of theory).

EXAMPLES

Physical Part

EXAMPLE 1

The substance B4 according to the invention is used for constructing an organic light emitting diode (OLED). The OLED is produced as follows:

1. Cleaning the ITO substrate

ITO-coated glass (Merck Balzers AG, Principality of Lichtenstein, Part. No. 253 674 XO) is cut into 50 mm×50 mm pieces (substrates). The substrates are subsequently cleaned in a 3% strength aqueous Mukasol solution in an ultrasonic bath for 15 minutes. The substrates are then rinsed with distilled water and spun dry in a centrifuge. This rinsing and drying procedure is repeated 10 times.

2. Application of the ®Baytron P layer to the ITO

About 10 ml of the 1.3% strength polyethylenedioxythiophene/polysulphonic acid solution (Bayer AG, Baytron P) are filtered (Millipore HV, 0.45 μm). The substrate is subsequently placed on a spin coater and the filtered solution is distributed on the ITO-coated side of the substrate. The excess solution is subsequently spun off by rotation of the plate at 500 rpm for a period of 3 minutes. The substrate which has been coated in this way is then dried at 110° C. for 5 minutes on a hotplate. The thickness of the layer is 60 nm (Tencor, Alphastep 200).

3. Application of the hole conduction layer

5 ml of a 1.0% strength solution of phenylamine (Agfa-Gevaert, compound A1) in THF are filtered (Millipore HV, 0.45 μm) and distributed on the dried Baytron P layer. The excess solution is subsequently spun off by rotation of the plate at 500 rpm for 60 seconds. The substrate which has been coated in this way is then dried at 110° C. for 5 minutes on a hotplate. The total thickness of the layer is 150 nm.

4. Vapour deposition of the light-emitting/electron-injecting layer

A third organic layer, namely the substance B4 according to the invention, is applied by thermal vapour deposition to the two organic layers produced in this way. This is carried out in a vapour deposition unit (Leybold, Univex 350). The pressure in the vapour deposition unit during vapour deposition is 10⁻³ Pa and the deposition rate is 2 Å/sec. The total thickness of the 3 organic layers is 200 nm.

5. Vapour deposition of the metal cathode

A metal electrode is vapour-deposited onto the organic layer system. For this purpose, the substrate is placed with the organic layer system downwards on a perforated mask (hole diameter: 5 mm). At a pressure of 10⁻³ Pa, the elements Mg and Ag are vaporized simultaneously from two vapour deposition boats. The deposition rates are 28 Å/sec for Mg. The thickness of the vapour-deposited metal contacts is 500 nm.

The two electrodes of the organic LED are connected to a power source via electric leads. The positive pole is connected to the ITO electrode, the negative pole is connected to the MgAg electrode.

Above a voltage of only 6 volt, electroluminescence can be detected by means of a photodiode (EG&G C30809E). At a voltage of 10 volt, the current per unit area is 1 mA/cm² and the electroluminescence is readily visible. The colour of the electroluminescence has the colour values x=0.3322; y=0.4570 (measured at 20 V) (spectrometer: CDI-PDA, Sentronic GmbH). 

What is claimed is:
 1. Electroluminescent assembly comprising a substrate, an anode, an electroluminescent element and a cathode, where at least one of the two electrodes is transparent in the visible spectral region and the electroluminescent element comprises one or more zones selected from the group consisting of a hole injection zone, a hole transport zone, an electroluminescent zone, an electron transport zone and an electron injection zone in the specified order, where each of the zones present may also assume functions of the other zones mentioned, characterized in that the electroluminescent element contains a thiophenecarboxylate-metal complex.
 2. Electroluminescent assembly according to claim 1, characterized in that the hole injection zone contains an uncharged or cationic polythiophene of the formula (I)

where Q¹ and Q² represent, independently of one another, hydrogen, substituted or unsubstituted (C₁-C₂₀)-alkyl, CH₂OH or (C₆-C₁₄)-aryl or Q¹ and Q² together represent —(CH₂)_(m)—CH₂— where m=0 to 12, preferably from 1 to 5, or (C₆-C₁₄)-arylene, and n represents an integer from 2 to 10,000, preferably from 5 to
 5000. 3. Electroluminescent assemblies according to claim 1, characterized in that the hole injection zone contains an uncharged or cationic polythiophene of the formula (Ia) or (Ib) or a mixture,

where Q³ and Q⁴ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₈)-alkyl, (C₂-C₁₂)-alkenyl, (C₃-C₇)-cycloalkyl, (C₇-C₁₅)-aralkyl, (C₆-C₁₀)-aryl, (C₁-C₁₈)-alkoxy or (C₂-C₁₈)-alkyloxy ester and Q⁵ and Q⁶ represent, independently of one another, hydrogen or (C₁-C₁₈)-alkyl, (C₂-C₁₂)-alkenyl, (C₃-C₇)-cycloalkyl, (C₇-C₁₅)-aralkyl, (C₆-C₁₀)-aryl, (C₁-C₁₈)-alkoxy or (C₂-C₁₈)-alkyloxy ester which are each substituted by at least one sulphonate group, where, if Q⁵ represents hydrogen, Q⁶ is not hydrogen and vice versa, n represents an integer from 2 to 10,000.
 4. Electroluminescent assemblies according to claim 3, characterized in that the cationic or uncharged polythiophenes correspond to the formulae (Ia-1) and (Ib-1),

where Q⁵ and n are as defined in claim
 3. 5. The electroluminescent assembly according to any one of claims 2 to 4 further including at least one of an anion of a polymeric carboxylic acid and a polymeric sulphonic acid as a polyanion.
 6. The electroluminescent assembly according to any one of claims 2 to 4 further including at least one of a polystyrenesulphonic acid and an alkaline earth metal salt thereof as a counterion.
 7. The electroluminescent assembly according to claim 1, wherein at least one of the hole injection and the hole transport zone contains an aromatic tertiary amino compound of the general formula (II)

wherein R² represents hydrogen, substituted or unsubstituted alkyl or halogen, R³ and R⁴ independently represent substituted or unsubstituted (C₁-C₁₀)-alkyl, alkoxycarbonyl-substituted (C₁-C₁₀)-alkyl or substituted or unsubstituted aryl, aralkyl or cycloalkyl.
 8. An electroluminescent assembly comprising a substrate, an anode, an electroluminescent element and a cathode, where at least one of the two electrodes is transparent in the visible spectral region and the electroluminescent element comprises one or more zones selected from the group consisting of a hole injection zone, a hole transport zone, an electroluminescent zone, an electron transport zone and an electron injection zone in the specified order, where each of the zones present may also assume functions of the other zones mentioned, characterized in that the electroluminescent element contains a thiophenecarboxylate-metal complex. wherein at least one of the hole injection and the hole transport zone contains an aromatic tertiary amino compound of the general formula (II)

wherein R² represents hydrogen or (C₁-C₆)-alkyl, R³ and R⁴ independently represent (C₁-C₆)-alkyl, (C₁-C₄)-alkoxycarbonyl-(C₁-C₆)-alkyl or unsubstituted or (C₁-C₄)alkyl- and/or (C₁-C₄)-alkoxy-substituted phenyl, naphthyl, phenyl-(C₁-C₄)-alkyl, naphthyl-(C₁-C₄)-alkyl, cyclopentyl or cyclohexyl.
 9. An electroluminescent assembly comprising a substrate, an anode, an electroluminescent element and a cathode, where at least one of the two electrodes is transparent in the visible spectral region and the electroluminescent element comprises one or more zones selected from the group consisting of a hole injection zone, a hole transport zone, an electroluminescent zone, an electron transport zone and an electron injection zone in the specified order, where each of the zones present may also assume functions of the other zones mentioned, characterized in that the electroluminescent element contains a thiophenecarboxylate-metal complex. wherein at least one of the hole injection and the hole transport zone contains an aromatic tertiary amino compound of the general formula (II) wherein the tertiary amino compound is selected from among the following compounds:


10. Electroluminescent assembly according to claim 1, characterized in that the thiophenecarboxylate-metal complex is a compound selected from among the general formulae (III) a to (III) g

where Me represents a metal, V₁, V₂, V₃ and V₄ each represent a substituted or unsubstituted and/or branched or unbranched alkylene radical or a substituted or unsubstituted thiophene or oligothiophene radical, V₅ represents an alkylene radical or a single bond, Z represents atoms which complete a moiety which comprises at least 2 fused rings, R₁ to R₁₀ represent, independently of one another, hydrogen or substituted or unsubstituted (C₁-C₁₆)-alkyl or (C₁-C₁₀)-alkoxy, and n represents an integer.
 11. Electroluminescent assembly according to claim 10, characterized in that Me is a trivalent metal which forms chelates.
 12. Electroluminescent assembly according to claim 1, characterized in that the transparent binder is selected from the group consisting of polycarbonates, polyester carbonates, copolymers of styrene, polysulphones, polymers based on vinyl-containing monomers, polyolefins, cyclic olefin copolymers and phenoxy resins.
 13. Electroluminescent assembly according to claim 1, characterized in that the thiophenecarboxylate-metal complex is selected from among the following compounds: 